Wavelength discriminators are incorporated in optical fibers by writing transverse holographic gratings into the fibers with a UV laser which sets up interference patterns within germanium-doped light guiding regions of the fibers. Such discriminators are employed in patents such as U.S. Pat. Nos. 5,048,913; 5,191,458; and 5,307,437 incorporated herein by reference. Wavelength discriminators have numerous applications and are used in such varied technologies as telecommunications, aerospace and medical devices.
To date, no wavelength standard has been established to provide precise modulation spacing of these transverse holographic gratings. The only high precision method to determine the resonant wavelengths is to monitor the final reflective wavelength response function. A major consequence of this lack of standardization and the resulting lack of precision in the spacing of Bragg reflection filters is an inability to set light probes and optical sensors at the proper wavelength regions to provide maximum photonic response for devices which operate within the transmission spectrum of optical fibers. Since there is no known wavelength standard, the writing locations for Bragg regions cannot be instantly or automatically calibrated. Accordingly, wavelength division multiplexed devices used to send and receive signals, cannot be set at appropriate spectral positions, or in optical location.